This application claims priority of Korean Patent Application No. 2004-28729, filed on Apr. 26, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1 Field of the Invention
The present invention relates to a video presenter for inputting a video image of an object, the presenter having a camera support structure allowing adjustment of camera orientation.
2 Description of the Related Art
A video presenter is a device that typically uses a charge-coupled device (CCD) camera and a magnifying lens to display images of an object on a display device.
The video presenter can be manufactured in a variety of configurations according to the supporting structure of the camera. The camera supporting structure has an adjustment function for allowing the CCD camera mounted on the support arm to access the object from various angles according to the desire and necessity of the users. For that, the supporting structure usually provides multiple degrees of freedom permitting movement of the supporting arm to a large degree. However, in a conventional video presenter, such a camera support structure has known limitations as described herein below.
In a conventional camera support structure, the camera head is fixed at an upper end of a support shaft which extends upwardly from a table for placing a photographing object thereon. This known structure provides the advantage of fixing the camera in a stable position, but causes restriction on viewing when in particular the object is quite large.
In another conventional camera support structure, the camera head is fixed on an upper end of a support shaft that is mounted in a sloped or diagonal direction from a corner of the presenter table. In this arrangement, the size of the table for placing an object can be reduced, but it is difficult to locate the camera accurately on the center of the table. Some additional components are typically required to eliminate this drawback.
Japanese Patent Laid-Open Publication No. 7-10377 discloses a video presenter having a two-part support arm (i.e., with upper and lower arm members) for supporting a camera head. In this presenter, the lower arm can be rotated with respect to a table. The upper arm is in turn rotatably connected to the lower arm via a joint. In addition, the camera head can also be rotated with respect to the upper arm. However, the upper and lower arm members are designed to rotate only in one direction. Moreover, the arm must be refrained from excessive rotation when it approaches the table due to the volume of the camera.
According to the above identified Japanese patent disclosure, the support arm may include a locking mechanism, and the arm can be rotated when an operator presses a lock button. Here, however, the operator should also hold the camera to prevent the camera from falling and damaging the equipment.
Korean Patent Laid-Open Publication No. 2003-0088520 to the present inventor discloses a camera support structure to solve this problem as discussed herein below.
Referring to FIG. 1, a camera support device 10 of a video presenter includes a shaft unit 32 mounted to a bracket 31 which is fixed to a camera head 15a, and a shaft receiving unit 24 for receiving the shaft unit 32 therein, which is attached at an upper end of a support arm 20 extending upwardly from a table of the video presenter. The camera support device 10 further includes a fixing plate 36 fixed to the shaft unit 32 and contacting a proximal face of an annular portion (not shown) of the shaft receiving unit 24, springs 35a and 35b disposed between the fixing plate 36 and the annular portion of the shaft receiving unit 24, and a cover 37 covering the proximal end of the shaft receiving unit 24. A friction ring 33 is disposed between the distal portion of the cylindrical shaft unit 32 and the annular portion of the shaft receiving unit 24.
The springs 35a and 35b are formed respectively in a half ring shape, and each has two curved protrusion portions 81 and a protrusion groove 82 between the two curved protrusion portions 81. An elastic force is generated when the curved protrusion portions 81 are pressed. Accordingly, the springs 35a and 35b are seated on a spring seating groove (not shown) of the annular portion of the shaft receiving unit 34.
Free rotation of the camera is prevented by a force generated between the fixing plate 36 and a bottom surface of the shaft receiving unit 34 by the elastic force of the springs 35a and 35b. The camera head 15a can be rotated by providing an external force greater than the elastic force of the springs 35a and 35b. 
Therefore, the camera head 15a can be maintained in a fixed position by the springs 35a and 35b as long as an external force is not applied to the camera.
Accordingly, an operator can use a video presenter having the camera support structure 10 with ease and without risking to damage the camera or the table or main body of the video presenter.
However, the elastic force of the springs 35a and 35b used for preventing the free rotation of the camera can be decreased from extended use if the camera is frequently moved, thereby incomplete fixing of the camera can occur. In particular, due to the weight of the camera, when the camera is fixed in a horizontal orientation, the springs 35a and 35 may not prevent free rotation of the camera after extended use of the presenter.